Cathode finger structure for an electrolytic cell

ABSTRACT

Novel cathode fingers are provided for an electrolytic cell which can enable the electrolytic cell to be designed to operate as a chlor-alkali diaphragm cell at high current capacities of about 150,000 amperes and upward to about 200,000 amperes while maintaining high operating efficiencies. These high current capacities provide for high production capacities which result in high production rates for given cell room floor areas and reduce capital investment and operating costs. The cathode finger structure comprises a corrugated conductive reinforcing member having protrusions on the outer surfaces of the corrugations, lengths of highly conductive metal, such as copper which can be attached to the reinforcing member, and a foraminous conductive member attached to the protrusions of the reinforcing member and acting as the outer cathode surface.

United States Patent Evans et al.

CATHODE FINGER STRUCTURE FOR AN ELECTROLYTIC CELL Inventors: Leo G.Evans, Tonawanda; Walter W. Ruthel, Grand Island, both of N.Y.

Assignee: Hooker Chemicals & Plastics Corporation, Niagara Falls, N.Y.

Filed: Jan. 3, 1974 Appl. No.: 430,430

[52] US. Cl. 204/286; 204/283; 204/284 [51] Int. Cl B0lk 3/04 [58] Fieldof Search 204/242, 252, 258, 266, 204/270, 278, 283, 284, 286

[56] References Cited UNITED STATES PATENTS 2,447,547 8/1948 Stuart204/266 3,342,717 9/1967 Leduc 204/266 X 3,493,487 2/1970 Ruthel et al.204/284 3,755,108 Raetzsch et al 204/256 X Primary Examiner-John l-l.Mack Assistant ExaminerW. l. Solomon Attorney, Agent, or FirmPeter F.Casella ABSTRACT Novel cathode fingers are provided for an electrolyticcell which can enable the electrolytic cell to be designed to operate asa chlor-alkali diaphragm cell at high current capacities of about150,000 amperes and upward to about 200,000 amperes while maintaininghigh operating efficiencies. These high current capacities provide forhigh production capacities which result in high production rates forgiven cell room floor areas and reduce capital investment and operatingcosts. The cathode finger structure comprises a corrugated conductivereinforcing member having protrusions on the outer surfaces of thecorrugations, lengths of highly conductive metal, such as copper whichcan be attached to the reinforcing member, and a foraminous conductivemember attached to the protrusions of the reinforcing member and actingas the outer cathode surface.

6 Claims, 8 Drawing Figures PATENTED AUG 1 21975 SHEET 2 PATENTEU Ann}2197:;

0 O Q 0 O Q O O O O O 0 O O O O O O O O O O O O O 0 O CATHODE FINGERSTRUCTURE FOR AN ELECTROLYTIC CELL BACKGROUND OF THE INVENTION Thisapplication is related to U.S. Pat. No. 3,859,196, which discloses anelectrolytic cell provided with the cathode fingers claimed in thisapplication.

This invention relates to novel cathode fingers for electrolytic cellssuited for the electrolysis of aqueous solutions. More particularly,this invention relates to novel cathode fingers for electrolytic cellssuited for the electrolysis of aqueous alkali metal chloride solutions.

Electrolytic cells have been used extensively for many years for theproduction of chlorine, chlorates, chlorites, hydrochloric acid,caustic, hydrogen and other related chemicals. Over the years, suchcells have been developed to a degree whereby high operatingefficiencies have been obtained, based on the electricity expended.Operating efficiencies include current, decomposition, energy, power andvoltage efficiencies. The most recent developments in electrolytic cellshave been in making improvements for increasing the productioncapacities of the individual cells while maintaining high operatingefficiencies. This has been done to a large extent by modifying orredesigning the individual cells and increasing the current capacitiesat which the individual cells operate. The increased productioncapacities of the individual cells operating at higher currentcapacities provide higher production rates for given cell room floorareas and reduce capital investment and operating costs.

In general, the most recent developments in electrolytic cells have beentowards larger cells which have high production capacities and which aredesigned to operate at high current capacities while maintaining highoperating efficiencies. Within certain operating parameters, the higherthe current capacity at which a cell is designed to operate, the higheris the production capacity of the cell. As the designed current capacityof a cell is increased, however, it is important that high operatingefficiencies be maintained. Mere enlargement of the component parts of acell designed to operate at low current capacity will not provide a cellwhich can be operated at high current capacity and still maintain highoperating efficiencies. Numerous design improvements must beincorporated into a high current capacity cell so that high operatingefficiencies can be maintained and high production capacity can beprovided.

Because the present invention may be used in many different electrolyticcells of which chlor-alkali cells are of primary importance, the presentinvention will be described more particularly with respect tochloralkali cells and most particularly with respect to chloralkalidiaphragm cells. However, such descriptions are not to be understood aslimiting the usefulness of the present invention with respect to otherelectrolytic cells.

In the early prior art, chlor-alkali diaphragm cells were designed tooperate at relatively low current capacities of about 10,000 amperes orless and had correspondingly low production capacities. Typical of suchcells is the Hooker Type S Cell, developed by the Hooker ChemicalCorporation, Niagara Falls, N.Y., U.S.A., which was a major breakthroughin the electrochemical art at its time of development and initial use.

The Hooker Type S Cell was subsequently improved by Hooker in a seriesof Type S Cells such as the Type S-3, S-3A, S-3B, S-3C, S-3D and S-4,whereby the improved cells were designed to operate at progressivelyhigher current capacities of about l5,000, 20,000, 25,000, 30,000,40,000 and upward to about 55,000 amperes with correspondingly higherproduction capacities. The design and performance of these Hooker Type Scells are discussed in Shreve, Chemical Process Industries, ThirdEdition, Pg. 233 (1967), McGraw-Hill; Mantell, IndustrialElectrochemistry, Third Edition, Pg. 434 (1950), McGraw-Hill; andSconce, Chlorine, Its Manufacture, Properties and Uses, A.C.S.Monograph, Pp. 94-97 (1962), Reinhold. U.S. Pat. No. 2,987,463 by Bakeret al. issued June 6, 196i to Diamond Alkali discloses a chlor-alkalidiaphragm cell designed to operate at a current capacity of about 30,000amperes which is somewhat different than the Hooker Type S series cells.U.S. Pat. No. 3,464,912 by Emery et al. issued Sept. 2, 1969 to Hookerand U.S. Pat. No. 3,493,487 by Currey et al. issued Nov. 2, 1971 toHooker disclose chlor-alkali diaphragm cells designed to operate at acurrent capacity of about 60,000 amperes.

The above description of the prior art shows the development ofchlor-alkali diaphragm cell design to provide cells which operate athigher current capacities with correspondingly higher productioncapacities. Chlor-alkali diaphragm cells have now been developed whichoperate at high current capacities of about 150,000 amperes and upwardto about 200,000 amperes with correspondingly higher productioncapacities while maintaining high operating efficiencies.

SUMMARY OF THE INVENTION In according with the present invention, thereare provided novel cathode fingers for an electrolytic cell. The novelcathode fingers have a novel cathode finger structure.

The novel cathode finger structure comprises a conductive metal cathodefinger reinforcing means, lengths of highly conductive metal positionedin the cathode finger structure and foraminous conductive metal meansattached to the cathode finger reinforcing means thereby forming theexterior of the cathode finger structure and gas compartment spaceinside the cathode finger structure. The cathode finger re .nforcingmeans can be provided with a suitable number of pegs, pins orprotrusions. The foraminous conductive metal means can be attached tothese protrusions and thereby provide additional compartment space forgas, formed at the cathode during electrolysis, to be channeled to acollection chamber.

The highly conductive metal is preferably positioned on the cathodefinger reinforcing means in the cathode finger structure and means isprovided for attaching the highly conductive metal to the cathode fingerreinforcing means. The highly conductive metal is positioned in thecathode finger structure in such a configuration whereby the lengths ofhighly conductive metal are adapted to carry an electric current and tomaintain a substantially uniform current density through the cathodefinger structure without any significant voltage drop across the cathodefinger structure and with the most economical power consumption in thecathode finger structure.

The novel cathode finger structure provides novel cathode fingers. Thecathode walled enclosure contains a plurality of cathode fingers whichextend substantially across the interior of the cathode walled enclosureand the cathode fingers are attached in electrical contact to at leastone interior sidewall of the cathode walled enclosure. The cathodebusbar structure is attached in electrical contact to the exteriorsidewall of the cathode walled enclosure adjacent to the attachedcathode fingers.

Means are provided for positioning the opposite ends of the cathodefingers adjacent to the interior sidewall of the cathode walledenclosure which is opposite to the interior sidewall where the cathodefingers are attached. v

An electrolytic cell provided with the novel cathode fingers of thepresent invention may be used in many different electrolytic processes.The electrolysis of aqueous alkali metal chloride solutions is ofprimary importance and the electrolytic cell of the present inventionwill be described more particularly with respect to this type ofprocess. However, such description is not intended to be understood aslimiting the usefulness of the cathode fingers of the present inventionor any of the claims covering the cathode fingers of the presentinvention.

DESCRIPTION OF THE DRAWINGS The present invention will be more fullydescribed by reference to the drawings in which:

FIG. 1 is an elevation view of an electrolytic cell and shows a cathodebusbar structure;

FIG. 2 is an enlarged partial sectional side elevation view of the cellof FIG. 1 along plane 2-2 and shows another view of the cathode busbarstructure;

FIG. 3 is an enlarged partial plan view of the cathode walled enclosureof the cell of FIG. 1 and shows the relative position of the cathodefingers.

FIG. 4 is an enlarged partial sectional and elevation view of thecathode fingersand the cathode walled enclosure of the cell of FIG. 3along plane 44 and shows the relative position of the cathode fingersand anode blades as positioned at the end of the cathode walledenclosure; f

FIG. 5 is an enlarged sectional side elevation view of a cathode fingerand the cathode walled enclosure of the cell of FIG. 3 along plane 55 'and shows the conshows the visible configuration of the highly conductivemetal positioned thereon;

FIG. 7 is a side elevation view of another embodiment of a cathodefinger reinforcing means and shows the configuration of the highlyconductive metal positioned thereon;

FIG. 8 is an end elevation view of the cathode finger reinforcing meansof FIG. 7 along plane 88 and shows the configuration of the highlyconductive metal positioned thereon and the peg or pin means;

FIGS. 3, 4, 5, 6, 7 and 8, when viewed together, show typicalembodiments of cathode finger structures.

Two different types of metals are used to fabricate most of the variouscomponents or parts which comprise the novel cathode fingers of thepresent invention. One of these types of metals is a highly conductivemetal. The other type of metal is a conductive metal which has goodstrength and structural properties.

The term highly conductive metal is herein defined as a metal which hasa low resistance to the flow of electric current and which is anexcellent conductor of electric current. Suitable highly conductivemetals include copper, aluminum, silver and the like and alloys thereof.The preferred highly conductive metal is copper or any of its highlyconductive alloys and any mention of copper in this application is to beinterpreted to mean that any other suitable highly conductive metal canbe used in the place of copper or any of its highly conductive alloyswhere it is feasible or practical.

The term conductive metal is herein defined as a metal which has amoderate resistance to the flow of electric current but which is still areasonably good conductor of electric current. The conductive metal, inaddition, has good strength and structural properties. Suitableconductive metals include iron, steel, nickel and the like and alloysthereof such as stainless steel and other chromium steels, nickel steelsand the like. The preferred conductive metal is a relatively inexpensivelow-carbon steel, hereinafter referred to simply as steel, and anymention of steel in this application is to be interpreted to mean thatany other suitable conductive metal can be used in the place of steelwhere it is feasible or practical.

The highly conductive metal and the conductive metal should haveadequate resistance or have adequate protection from corrosion duringoperation of the electrolytic cell.

Referring now to FIG. 1, electrolytic cell 11 comprises corrosionresistant plastic top 12, cathode walled enclosure 13 and cell base 14.Top 12 is positioned on cathode walled enclosure 13 and is secured tocathode walled enclosure 13 by fastening means (not shown). A seal ismaintained between top 12 and cathode walled enclosure 13 by means of asealing gasket. Cathode walled enclosure 13 is positioned on cell base14 and is secured to cell base 14 by fastening means (not shown). A sea]is maintained between cathode walled enclosure 13 and cell base 14 bymeans of an elastomeric sealing pad. Electrolytic cell 11 is positionedon legs 15 which are used as support means for the cell.

Cathode busbar structure 16 is attached in any suitable manner, as bywelding, to steel sidewall 17 of steel cathode walled enclosure 13.Cathode busbar structure 16 comprises copper lead-in busbar l8 and aplurality of copper busbar strips 19, 21 and 22 which have differentrelative dimensions and are positioned in such a configuration whereinlead-in busbar 18 and busbar strips 19, 21 and 22 are adapted to carryan electric current and to maintain a substantially uniform currentdensity through cathode busbar structure 16 to electrical contact pointson sidewall 17 of cathode walled enclosure 13.

Cathode busbar structure 16' can be provided with cooling means 23 whichcomprises steel plates 24, 25, 26 and 30 and steel entrance and exitports 27 and 28 fabricated in any suitable manner, as by welding, toform the said cooling means. Cooling means 23 is attached in anysuitable manner, as by welding, to lead-in busbar l8 and busbar strip19. Collant, preferably water, is circulated through cooling means 23 bypassage through entrance and exit ports 27 and 28. Cooling means 23 isprovided primarily for use when an electrolytic cell adjacent toelectrolytic cell 11 is jumpered and is removed from the electricalcircuit. The use of cooling means 23 permits considerably less copper tobe used in cathode busbar structure 16 which results in a substantialreduction in capital investment costs for cathode copper. While coolingmeans 23 is provided primarily for use when an electrolytic celladjacent to electrolytic cell 11 is jumpered, cooling means 23 can beused during routine cell operation either to cool cathode busbarstructure 16 during any periodic electric current overloads or tocontinuously cool cathode busbar structure 16, thereby permittingfurther reductions in the use of copper in cathode busbar structure 16with an accompanying reduction in capital investment costs for cathodecopper.

Lead-in busbar 18 can be provided with steel contact plates 29 and 31which serve as contact means. Steel contact plates 29 and 31 areattached to lead-in busbar 18 in any suitable manner, as by means ofscrews 32. Lead-in busbar 18 and steel contact plates 29 and 31 can beprovided with holes 33 which can serve as means for attaching intercellconnectors carrying electricity from an adjacent cell or leads carryingelectricity from another source to lead-in busbar 18. Lead-in busbar 18and busbar strip 19 can be used as a cathode jumper busbar when providedwith holes 34 which can serve as means for attaching cathode jumperconnectors when an adjacent electrolytic cell is jumpered and is removedfrom the electrical circuit. It is during this jumpering operation thatcooling means 23 can provide its greatest utility by preventing thetemperatures in cathode busbar structure 16 from rising to levelswhereby damage to cathode busbar structure 16 or other components ofelectrolytic cell 11 occurs.

Referring now to FIG. 2, cathode busbar structure 16 is shown in anotherview and the description of this figure further describes cathode busbarstructure 16 including the configuration and the different relativedimensions of the components or parts comprising cathode busbarstructure 16 which were described in FIG.

Cathode busbar structure 16 comprises copper leadin busbar 18 and aplurality of copper busbar strips 19, 21 and 22. Busbar strips 19, 21and 22 are attached to steel sidewall 17 of steel cathode walledenclosure 13 in any suitable manner, as by means of copper to steelwelds 35, 37, 38 and 41, and to one another in any suitable manner, asby means of copper to copper welds 36 and 39. The weld metal ispreferably of the same metal as the busbar strips, that is, copper. Thismeans of attaching the busbar strips to sidewall 17 greatly decreasesthe required weld area and forms a lower electrical contact resistanceto sidewall 17 or the cathode steel. Lead-in busbar 18 is attached tobusbar strip 19 in any suitable manner, as by means of copper to copperweld 42, and lead-in busbar 18 is attached to sidewall 17 in anysuitable manner, as by means of steel blocks 43. Lead-in busbar 18 isattached to steel blocks 43 in any suitable manner, as by a combinationof screws (not shown), and steel blocks 43 are attached to sidewall 17of cathode walled enclosure 13 in any suitable manner, as by means ofsteel to steel welds 40. Steel contact plates 29 and 31 are attached tolead-in busbar 18 in any suitable manner, as by means of screws 32.

The above means of attachment provides a cathode busbar structurewherein lead-in busbar l8 and the plurality of busbar strips 19, 21 and22 are attached and electrically interconnected by means of welds 36,37, 38, 39 and 42 and cathode busbar structure 16 is attached inelectrical contact to sidewall 17 of cathode walled enclosure 13 bymeans of welds 35, 37, 38, 40 and 41.

Cathode fingers 44 are attached in electrical contact to sidewall 17 inany suitable manner, as by welding cathode finger reinforcing means 45to sidewall 17. A typical cathode finger 44 is partially shown. Cathodefinger 44 comprises steel cathode finger reinforcing means 45 andperforated steel plates 46 which are attached in any suitable manner, asby welding. Perforated steel plates 47 are attached in any suitablemannet, as be welding, to perforated steel plates 46 and sidewall 17,thereby forming peripheral chamber 48.

The height of the plurality of the busbar strips at their points ofattachment to sidewall 17 is usually substantially equal to the heightof cathode finger reinforcing means 45 at their points of attachment tosidewall 17. This height can be further defined as being of more thanabout one-half of the height of cathode walled enclosure 13. Thethickness of busbar strips 21 and 22 are preferably less than those oflead-in busbar 18 and busbar strip- 19.

The cathode finger reinforcing means are preferably corrugatedstructures fabricated from steel sheet, however, other suitablereinforcing means such as conductive metal bars, plates, reinforcedsheets and the like can also be used. The cathode finger reinforcingmeans serve the dual functions of first, supporting and reinforcing theperforated steel plates, and second, carrying electrical current to allsections of the perforated steel plates with a minimum electricalresistance through the cathode finger reinforcing means.

The foraminous conductive metal means used to form the cathode fingersand the peripheral chamber are preferably perforated steel plates butcan be steel screens. Other suitable foraminous conductive metal meanswhich can be used to form the cathode fingers and the peripheral chamberincludes conductive metal grids, meshes, screens wire cloths or thelike.

Cathode walled enclosure 13 is positioned on cell base 14 and is securedto cell base 14 by fastening means (not shown). Cell base 14 compriseselastomeric sealing pad 49 and conductive anode base 51, and, if needed,structural support means 52. A seal is maintained between cathode walledenclosure 13 and cell base 14 by means of elastomeric sealing pad 49.

In a typical circuit of electrolytic cells, electric current is carriedthrough intercell connectors (not shown) to lead-in busbar 18 of cathodebusbar structure 16. Electric current is then carried and asubstantially uniform current density is maintained through cathodebusbar structure 16 without any significant voltage drop across cathodebusbar structure 16 and with the most economical power consumption incathode busbar structure 16. Electric current is carried and asubstantially uniform current density is maintained through cathodebusbar structure 16 by means of the configuration and the differentrelative dimensions of lead-in busbar 18 and busbar strips 19, 21 and22. Electric current is thus carried through cathode busbar structure 16to electrical contact points on sidewall 17 of cathode walled enclosure13 where it is distributed to cathode fingers 44 and, under theseconditions, the electric current is readily carried to all sections ofperforated steel plates 46 with a minimum electrical resistance throughcathode finger reinforcing means 45.

The cathode busbar structure makes the most economic use of investedcapital, namely, the amount of copper or other suitable highlyconductive metal used in the cathode busbar structure. The configurationand different relative dimensions of the lead-in busbar or busbars andthe plurality of busbar strips significantly reduce the amount of copperor other suitable highly conductive metal required in the cathode busbarstruc' ture as compared to the prior art. The lead-in busbar or busbarsand the pluarlity of busbar strips by means of their configuration anddifferent relative dimensions are also adapted to carry an electriccurrent and to maintain a substantially uniform current density throughthe cathode busbar structure.

The configuration and dimensions of the lead-in busbar or busbars andthe plurality of busbar strips can vary depending on the designedcurrent capacity of the electrolytic cell and also can vary depending ona number of factors such as the current density, the conductivity of themetal used, the amount of weld area, the fabrication costs and the like.

The cathode busbar structure provides improved electrical conductivityto the immediate area of the cathode fingers, thereby providing aminimum or no significant voltage drop across the cathode busbarstructure with a substantial reduction in copper or other suitablehighly conductive metal expenditures as compared to the prior art.

The cathode busbar structure can enable an electrolytic cell to bedesigned to operate as a chlor-alkali diaphragm cell at high currentcapcities of about 150,000 amperes and upward to about 200,000 ampereswhile maintaining high operating efficiencies. These high currentcapacities provide for high production capacities which result in highproduction rates for given cell room floor areas and reduce capitalinvestment and operating costs. In addition to being capable ofoperation at high amperages, an electrolytic cell can also efficientlyoperate at lower amperages, such has about 55,000 amperes using thecathode busbar structure.

Referring now to FIG. 3, cathode fingers 44 are enclosed by steelsidewalls 17, 54, 55 and 56 of steel cathode walled enclosure 13. Theplurality of cathode fingers 44 can be any number from about 10 to about50 or more, preferably the number is about to about 40 and morepreferably the number is about to about 30. The anode blades (not shown)are positioned between cathode fingers 44. Perforated steel plates 46are attached in any suitable manner, as by welding, to steel cathodefinger reinforcing means 45. Steel plates 53 are also attached in anysuitable manner, as by welding, to cathode finger reinforcing means 45.Cathode fingers 44 are attached to steel sidewall 17 in any suitablemanner, as by welding steel plates 53 and cathode finger reinforcingmeans 45 to sidewall 17. Perforated steel plates 47 are attached tosidewalls 17, 54, 55 and 56 and to perforated steel plates 46 in anysuitable manner, as by .welding. Perforated steel plates 47 surround theinner sidewalls of cathode walled enclosure 13 and form peripheralchamber 48 which serves as a collection chamber for, hydrogen gas formedat the cathode during electrolysis. Hydrogen gas formed at the cathodeduring electrolysis is channeled across cathode fingers 44 to peripheralchamber 48 from whence it proceeds to gas withdrawal means 57.

Referring now to FIG. 4, perforated steel plates 46 are attached in anysuitable manner, as by welding, to

steel cathode finger reinforcing means 45. Steel plates 53 are attachedin any suitable manner, as be welding, to cathode finger reinforcingmeans 45. Steel support means 58 are attached in any suitable manner, asby welding, to cathode finger reinforcing means 45 and to sidewall 56 ofsteel cathode walled enclosure 13. Perforated steel plates 47 areattached in any suitable manner, as by welding, to perforated steelplates 46 and to sidewalls l7 and 56 thereby forming peripheral chamber48. Because of the larger dimensions of this figure, peripheral chamber48 is more clearly shown. Cathode finger reinforcing means 45 can beprovided with protrusions 59 and perforated steel plates 46 can beattached in any suitable manner, as by welding, to protrusions 59thereby providing additional compartment space for hydrogen gas, formedat the cathode during electrolysis, to be channeled to peripheralchamber 48.

Steel tips 61 and steel plates 53 are attached in any suitable manner,as by welding, to copper rods 62. Steel tips 61 and steel plates 53 areattached in any suitable manner, as by welding, to cathode fingerreinforcing means 45 thereby positioning copper rods 62 on cathodefinger reinforcing means 45.

Cathode finger reinforcing means 45 are preferably corrugated structuresfabricated from sheet steel, however, other suitable reinforcing meanssuch as bars, plates, reinforced sheets and the like can also be used.Cathode finger reinforcing means 45 serve the dual functions of first,supporting and reinforcing perforated steel plates 46, and second,carrying electric current to all sections of perforated steel plates 46with a minimum electrical resistance through cathode finger reinforcingmeans 45.

Referring now to FIGS. 2 and 4, cathode walled enclosure 13 ispositioned on cell base 14 and is secured to cell base 14 by fasteningmeans (not shown). Cell base 14 comprises conductive anode base 51 and,if needed, suitable structural support means 52. A sea] is maintainedbetween cathode walled enclosure 13 and cell base 14 by means ofelastomeric sealing pad 49.

Anode blades 72 are preferably metallic anode blades and are attached inelectrical contact to conductive anode base 51 in any suitable manner,as by means of nuts and/or bolts, secured projections, studs, welding orthe like. Cathode fingers 44 are spaced adjacent to each other at such adistance whereby anode blades 72 are centered between adjacent cathodefingers 44 and the desired alignment distance between anode blades 72and cathode fingers 44 is provided.

Referring now to FIGS. 2, 3 and 4, electrolytic cell 11 is particularlyuseful for the electrolysis of alkali metal chloride solutions ingeneral, including not only sodium chloride, but also potassiumchloride, lithium chloride, rubidium chloride and cesium chloride. Whenelectrolytic cell 11 is used to electrolyze such solutions, electrolyticcell 11 is provided with diaphragm 71 which serves to form separateanolyte and catholyte compartments so that chlorine is formed at theanode and caustic and hydrogen are formed at the cathode. Diaphragm 71comprises a fluid-permeable and halogen-resistant material which coverssteel plates 46 forming cathode fingers 44 and perforated steel plates47 forming peripheral chamber 48. Preferably, diaphragm 71 is asbestosfiber deposited in place on the outer surfaces of perforated steelplates 46 and 47. Electrolytic cell 11 is adapted to permit the use ofmany types of diaphragms, including asbestos fabric,

asbestos paper, asbestos sheet and other suitable materials known tothose skilled in the art.

Perforated steel plates 46 forming cathode fingers 44 and perforatedsteel plates 47 forming peripheral chamber 48 are foraminous conductivemetal means. Other suitable foraminous conductive metal means which canbe used to form the cathode fingers and the peripheral chamber includeconductive metal grids, meshes, screens, wire cloths or the like.

Referring now to FIGS. 3 and 5, some of the details described in theforegoing figures are more clearly shown in these figures. Cathodebusbar structure 16 is attached to outer sidewall 17 of cathode walledenclosure 13 and the ends of cathode fingers 44 adjacent thereto areattached to inner sidewall 17 of cathode walled enclosure 13 in themanner or manners described in the foregoing figures.

The other ends of cathode fingers 44 are preferably positioned asfollows: Posterior ends 63 of steel cathode finger reinforcing means 45are positioned adjacent to steel sidewall 55 of steel cathode walledenclosure 13 by means of steel support members 64, 65, 66 and 67.Support members 64 and 65 are attached in any suitable manner, as bywelding, to cathode finger reinforcing means 45 and rest upon supportmembers 66 and 67 which are attached in any suitable manner, as bywelding, to sidewall 55. Support members 64 and 65 can be attached orfastened to support members 66 and 67, respectively, however, it ispreferred that support members 64 and 65 not be attached or fastened sothat both linear and horizontal thermal expansion and- /or contractioncan be provided for cathode fingers 44.

Perforated steel plates 47 are attached in any suitable manner, as bywelding, to sidewalls 17, 54, 55 and 56, respectively, and to adjacentperforated steel plates 46 thereby forming peripheral chamber 48.

Copper rods 62 are preferably of different lengths and are preferablypositioned on cathode finger reinforcing means 45 as shown in FIG. 5.Steel tips 61 are attached in any suitable manner, as by welding, toends 68 of copper rods 62 and steel plate 53 is attached in any suitablemanner, as by welding, to linear ends 73 of copper rods 62 therebyforming cathode copper assembly 69. Cathode copper assembly 69 isattached to cathode finger reinforcing means 45 in any suitable manner,as by welding steel tips 61 and steel plate 53 to steel cathode fingerreinforcing means 45. Copper rods 62 can thus be positioned on cathodefinger reinforcing means 45. Copper rods 62 are of sufficient length andpreferably are of different lengths to maintain substantially uniformcurrent density through cathode finger 44. Copper rods 62 do notnecessarily have to be round or uniform in cross-section and can besquare, rectangular, hexagonal, octagonal or the like in cross-sectionand can vary in cross-section along their lengths. It is important,however, that copper rods 62 be of sufficient length and cross-sectionto carry an electric current and to maintain a substantially uniformcurrent density through cathode fingers 44 without any significantvoltage drop across cathode fingers 44 and with the most economicalpower consumption in cathode fingers 44.

The use of a suitable highly conductive metal, such as copper, incathode fingers 44 as shown in FIGS. 4, 5, 6, 7 and 8 is considered tobe a novel use of a suitable highly conductive metal in the cathodefingers. The use of copper in the cathode fingers is disclosed in US.Pat.

No. 3,464,912 by Emery et al. issued Sept. 2, 1969 to Hooker and US.Pat. No. 3,493,487 by Ruthel et al. issued Feb. 3, 1970 to Hooker,however, these disclosed uses of copper in the cathode fingers do notdisclose, much less teach, the use of copper in the cathode fingers ofan electrolytic cell in the manner as taught herein.

The preferred method of positioning copper rods 62 on cathode fingerreinforcing means 45 and in cathode fingers 44 is also novel. Steel tips61 are welded to ends 68 of copper rods 62 and steel plate 53 is weldedto linear ends 73 of copper rods 62 thereby forming cathode copperassembly 69. Any warpage from the welding of steel tips 61 and steelplate 53 to copper rods 62 is corrected or compensated for beforecathode copper assembly 69 is attached to cathode finger reinforcingmeans 45. Cathode copper assembly 69 is attached to cathode fingerreinforcing means 45 by welding steel tips 61 and steel plate 53 tosteel cathode finger reinforcing means 45. Copper rods 62 are thuspositioned on cathode finger reinforcing means 45 and in cathode fingers44. In this manner, all the copper to steel welds are made prior to thewelding of cathode copper assembly 69 to cathode finger reinforcingmeans 45 and any metal warpage from welding is substantially eliminated.

The novel cathode fingers can enable an electrolytic cell to be designedto operate as a chlor-alkali diaphragm cell at high current capacitiesof about 150,000 amperes and upward to about 200,000 amperes whilemaintaining high operating efficiencies. These high current capacitiesprovide for high production capacities which result in high productionrates for given cell room floor areas and reduce capital investment andoperating costs. In addition to being capable of operation at highamperages, an electrolytic cell can also efficiently operate at loweramperages, such as about 55,000 amperes using the novel cathode fingers.

Referring now to FIG. 6, the opposite side of cathode finger reinforcingmeans 45 shown in FIG. 5 is shown and the visible configuration ofcopper rods 62 positioned thereon is also shown. Cathode copper assembly69 which comprises copper rods 62, steel plate 53 and steel tips 61 isshown positioned on cathode finger reinforcing means 45 Cathode fingerreinforcing means 45 can be provided with protrusions 59- and perfc itedsteel plates 46 can be attached in any suitable mt -ner, as by welding,to protrusions 59 thereby providi eg additional compartment space forhydrogen gas, (ormed at the cathode during electrolysis, to be channeledto peripheral chamber 48. Protrusions 59 are positioned at spacedintervals on cathode finger reinforcing means 45 and only arepresentative portion are shown in this figure.

Referring now to FIGS. 7 and 8, another embodiment of a cathode fingerreinforcing means is shown and a configuration of copper rods positionedthereon is also shown. In this embodiment, cathode finger reinforcingmeans 111 comprises steel plate 112 having steel peg or pin means 113extending therefrom. Cathode copper assembly 69 which comprises copperrods 62, steel plate 53 and steel tips 61 is shown positioned on steelplate 1 12 of cathode finger reinforcing means 111 with a portion ofsteel plate 112 removed to accommodate steel plate 53. Cathode copperassembly 69 is attached to cathode finger reinforcing means 111 in anysuitable manner, as by welding steel plate 53 and steel tips 61 to steelplate 1 l2. Perforated steel plates 46 can be attached in any suitablemanner, as by welding, to steel peg means 113 thereby providingcompartment space for hydrogen gas, formed at the cathode duringelectrolysis, to be channeled to peripheral chamber 48.

PREFERRED EMBODIMENTS The following Example illustrates the practice ofthe present invention and a mode of utilizing the present invention.

EXAMPLE therein are possible. It is further intended that each componentrecited in any of the following claims is to be understood as referringto all equivalent components for accomplishing the same results insubstantially the same or an equivalent manner. The following claims areintended to cover the present invention broadly in whatever form theprinciples thereof may be utilized.

What is claimed is:

1. A cathode finger, suitable for use in an electrolytic cell, whereinsaid cathode finger has a cathode finger structure which comprises acorrugated conductive metal reinforcing means, lengths of highlyconductive metal positioned in the cathode finger structure, andforaminous conductive metal means attached to said cathode fingerreinforcing means thereby forming the exterior of the cathode fingerstructure and providing a gas compartment space inside the cathodefinger structure, said corrugated conductive metal structure havingprotrusions positioned on the outer surfaces of its ridges to which saidforaninous conductive metal means is attached to provide additionalcompartment 150,000 Ampere Cell 84.000 Ampere Cell of the Prior ArtProvided with the Novel Cathode Fingers of the Present Invention "Thecells can be operated at lower caustic content in the cell liquor. Thiswill result in greater current efficiencies.

. novel cathode fingers of the present invention has a higher productionrate for a given cell room floor area, uses less operating labor andalso has a lower capital investment per ton of chlorine produced.

This example shows that an electrolytic cell can be designed to operateat a high current capacity to provide a high production capacity and ahigh production rate while maintaining high operating efficiencies.

An electrolytic cell provided with the novel cathode fingers of thepresent invention can have many other uses. For example, alkali metalchlorates can be produced using the electrolytic cell by furtherreacting the formed caustic and chlorine outside of the cell. In thisinstance, solutions containing both alkali metal chlorate and alkalimetal chloride can be recirculated to the electrolytic cell for furtherelectrolysis. The electrolytic cell can be utilized for the electrolysisof hydrochloric acid by electrolyzing hydrochloric acid alone or incombination with an alkali metal chloride. Thus, the electrolytic cellis highly useful in these and many other aqueous processes.

While there have been described various embodiments of the presentinvention, the apparatus described is not intended to be understood aslimiting the scope of the present invention. It is realized that changesspace for gas, said lengths of highly conductive metal are positioned inthe cathode finger structure in such a configuration wherein the lengthsof highly conductive metal are adapted to carry an electric current andto maintain a substantially uniform current density through the cathodefinger without any significant voltage drop across the cathode fingerand with the most economical power consumption in the cathode finger.

2. The cathode finger structure of claim 1 wherein said foraminousconductive metal means is perforated metal plate.

3. The cathode finger structure of claim 1 wherein the foraminousconductive metal means is screen.

4. The cathode finger structure of claim 1 wherein the lengths of highlyconductive metal are of different lengths and are positioned on thecathode finger reinforcing means in the cathode finger structure and thehighly conductive metal is attached to the cathode finger reinforcingmeans.

5. The cathode finger structure of claim 1 wherein the lengths of highlyconductive metal have different cross-sections and are positioned on thecathode finger reinforcing means in the cathode finger structure and thehighly conductive metal is attached to the cathode finger reinforcingmeans.

6. The cathode finger structure of claim 1 wherein the lengths of highlyconductive metal ahve different lengths and different cross-sections andare positioned on the cathode finger reinforcing means in the cathodefinger structure and the highly conductive metal is attached to thecathode finger reinforcing means.

1. A CATHODE FINGER, SUITABLE FOR USE IN AN ELECTROLYTIC CELL, WHEREINSAID CATHODE FINGER HAS A CATHODE FINGER STRUCTURE WHICH COMPRISES ACORRRUGATED CONDUCTIVE METAL REINFORCING MEANS, LENGTHS OF HIGHLYCONDUCTIVE METAL POSITIONED IN THE CATHODE FINGER STRUCTURE, ANDFORAMINOUS CONDUCTIVE METAL MEANS ATTACHED TO SAID CATHODE FINGERREINFORCING MEANS THEREBY FORMING THE EXTERIOR OF THE CATHODE FINGERSTRUCTURE AND PROVIDING A GAS COMPARTMENT SPACE INSIDE THE CATHODEFINGER STRUCTURE, SAID CORRUGATED CONDUCTIVE METAL STRUCTURE HAVINGPROTRUSIONS POSITIONED ON THE OUTER SURFACES OF ITS RIDGES TO WHICH SAIDFORANINOUS CONDUCTIVE METAL MEANS IS ATTACHED TO PROVIDE ADDITIONALCOMPARTMENT SPACE FOR GAS, SAID LENGTHS OF HIGHLY CONDUCTIVE METAL AREPOSITIONED IN THE CATHODE FINGER STRUCTURE IN SUCH A CONFIGURATIONWHEREIN THE LENGTHS OF HIGHLY CONDUCTIVE METAL ARE ADAPTED TO CARRY ANELECTRIC CURRENT AND TO MAINTAIN A SUBSTANTIALLY UNIFORM CURRENT DENSITYTHROUGH THE CATHODE FINGER WITHOUT ANY SIGNIFICANT VOLTAGE DROP ACROSSTHE CATHODE FINGER AND WITH THE MOST ECONOMICAL POWER CONSUMPTION IN THECATHODE FINGER.
 2. The cathode finger structure of claim 1 wherein saidforaminous conductive metal means is perforated metal plate.
 3. Thecathode finger structure of claim 1 wherein the foraminous conductivemetal means is screen.
 4. The cathode finger structure of claim 1wherein the lengths of highly conductive metal are of different lengthsand are positioned on the cathode finger reinforcing means in thecathode finger structure and the highly conductive metal is attached tothe cathode finger reinforcing means.
 5. The cathode finger structure ofclaim 1 wherein the lengths of highly conductive metal have differentcross-sections and are positioned on the cathode finger reinforcingmeans in the cathode finger structure and the highly conductive metal isattached to the cathode finger reinforcing means.
 6. The cathode fingerstructure of claim 1 wherein the lengths of highly conductive metal ahvedifferent lengths and different cross-sections and are positioned on thecathode finger reinforcing means in the cathode finger structure and thehighly conductive metal is attached to the cathode finger reinforcingmeans.